1. Field of the Invention
This invention relates in general to a color television camera system having a single color image pickup tube which uses a stripe filter for resolving the color components of an image.
2. Description of the Prior Art
It is well known in the art to provide a monotube image pickup device which is equipped with two or three colored striped filter arrangements in front of the color pickup tube. Such arrangement is shown, for example, in U.S. Pat. Nos. 4,030,118 and 4,041,528. In the image pickup device of these types, the video output signal is carrier modulated with a stripe filter so that its chrominance components have different phases or lie in different bands. In image pickup devices which use three colored striped filters, if the carrier frequencies of the respective chrominance components are arranged close to each other so that the luminance signal contained in the lower frequency band of the modulated video signal occupies a sufficiently wide band width the problem arises that the separation of each chrominance component becomes difficult and the cross-talk between the respective chrominance components increases. On the other hand, if the carrier frequency of each chrominance component is widely spaced, the high frequency component of the luminance signal becomes so restricted by the carrier component that the resolution of a picture is difficult and the picture becomes degraded. Also, a quasi-video signal or beat interference is generated due to the spectrum characteristic of the color filter used, as well as the .gamma.-characteristic of the photoelectric conversion device and other factors cause the picture to be degraded. In the image pickup devices using two colored stripe filters, the white balance and the balance of the color reproduction are liable to be destroyed because of the dark current of the image pickup tube as well as the non-linearity due to the degree of modulation wherein the degree of modulation is lowered as the amount of light is increased and the shading also destroys the balance so that complex compensating circuits are required and the system becomes instable.